1. Field of the Invention
The present invention relates to a gate valve apparatus of a vacuum processing system, to a semiconductor processing system including a plurality of process chambers, and to a method of using the system. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target object, such as a semiconductor wafer or a glass substrate used for an LCD (Liquid Crystal Display) or FPD (Flat Panel Display), by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target object.
2. Description of the Related Art
In general, in a fabrication process of a semiconductor device, various processes, such as dry etching, sputtering and CVD (Chemical Vapor Deposition), are repeatedly performed on a semiconductor wafer. Most of these processes are executed in a vacuum atmosphere, and transfer ports for loading/unloading the wafer in process chambers that execute these processes are airtightly sealed by gate valve apparatuses at the time of processes.
Patent Document 1 (Jpn. Pat. Appln. KOKAI Publication No. 8-60374), for instance, discloses an example of this type of gate value apparatus. For example, a transfer port with such a size as to permit passage of a wafer is formed in a side wall of a process chamber that can be evacuated. The transfer port is provided with a gate valve apparatus. At the time of executing a process, the transfer port is airtightly sealed by a valve body with, e.g. an O-ring of the gate valve apparatus.
The above-mentioned processes include a process using a corrosive gas. Even in the case where a corrosive gas is not used in the process, a cleaning process is periodically or nonperiodically performed using an etching gas, which is a corrosive gas, in order to remove various unnecessary films or contaminants adhering to the inside of the process chamber. In this case, a seal member of the gate valve apparatus is exposed to the corrosive gas, and the seal member is degraded, although such degradation progresses little by little. Further, the seal member is put in contact with, or pressed on, a seat surface, resulting in physical degradation such as wear or fatigue. This requires periodical/nonperiodical replacement of the seal member.
A plurality of the above-mentioned process chambers are, in general cases, coupled around a single common transfer chamber via gate valve apparatuses, thereby constituting a so-called “cluster tool”. A work for replacing the seal member of the gate valve apparatus is generally performed at the same time as a maintenance work that is performed in a state in which the inside of the process chamber that is disposed continuous to the gate valve apparatus is opened to the outside air. However, since the inside of the process chamber is opened to the outside air and the gate valve apparatus is opened for replacement of the seal member, the inside of the common transfer chamber is also opened to the outside air. At this time, the other process chambers are closed by the associated gate valve apparatuses.
In this case, after the completion of the maintenance work and the replacement of the seal member, each of the transfer chamber and the process chamber is evacuated and restored to a predetermined reduced-pressure atmosphere. However, if these chambers are once opened to the outside air, moisture or various impure gases in the air adhere to, e.g. the inner wall surfaces. A great deal of time for evacuation is needed in order to almost completely eliminate such adhering moisture and impure gases. As a result, a decrease occurs in operation rate of the apparatus and in throughput.
In order to solve this problem, there has been proposed a gate valve apparatus with two valve bodies, as disclosed in Patent Document 2 (PCT National Application Publication No. 2003-503844), for instance. Specifically, two driving mechanisms that are independently operable are disposed within the gate valve apparatus, and these driving mechanisms are provided with valve bodies. When maintenance for the inside of the process chamber is conducted or the seal member on the valve body side, which is exposed to the corrosive gas, is replaced, the port on the side of the common transfer chamber is airtightly sealed by the other valve body. Thereby, even if the inside of the process chamber is opened to the outside air, the inside of the transfer chamber can be kept in a vacuum state.
In this conventional gate valve apparatus, however, two sets of the valve body and driving mechanism have to be provided, resulting in a complex whole structure and an increase in size of the apparatus. Besides, when the seal member is replaced, it is necessary to disassemble the casing of the gate valve apparatus, etc. Consequently, the replacement work itself becomes a large-scale, time-consuming work. Furthermore, when the seal member is to be replaced, the inside of the gate valve apparatus has to be opened to the outside air. This causes the inside of the gate valve apparatus to be contaminated or increases the time necessary for evacuating the inside of the gate valve apparatus after the replacement work. In other words, the seal member cannot be replaced unless the inside of the process chamber is opened to the outside air.